Jet bit



July 4, 1967 w. J. NEILSON 3,329,222

INVENTOR.

United States Patent 3,329,222 JET BIT William J. Neilson, Whittier, Qalifi, assignor to Smith Industries International, Inc., Compton, Calif., a corporation of California Filed Nov. 23, 1964, Ser. No. 413,245 3 Claims. (Cl. 175340) The application is a continuation-in-part of my copending application Ser. No. 271,307 filed Apr. 8, 1963, entitled Jet Bits, and issued Sept. 21, 1965 as Patent No. 3,207,241.

This invention relates to improvements in well drilling bits and in particular to that class of bits commonly referred to as jet bits.

In the above identified application, there is disclosed a well drilling bit of the roller cutter type wherein one leg of the body which rotatably supports a rotary or roller cutter in a conventional bit construction is devoted to conducting circulation fluid to a point near the bottom of the hole being drilled by the remaining cutters so as to discharge a jet at high velocity thereagainst. As therein disclosed, the circulation fluid discharges from the circulation passage in the mentioned leg of the bit through a nozzle disposed within six of its internal diameters from the bottom of the hole so that the issuing stream of circulation fluid will not be dissipated prior to its encountering the bottom of the hole. As therein disclosed, the circulation fluid passage is largely provided by a tube disposed against the inner side of the leg, and thi tube has a discharge nozzle formed of a hard wear-resistant material mounted therein adjacent its lower end. The discharge nozzle which is formed of hard wear-resistant material is retained in place in the tube by a threaded gland or nut and the bottom surface of the discharge nozzle is disposed some distance above the bottom surface of the retaining gland or nut and even above the bottom surface of the leg.

It has been found that with a bit thus constructed, the backwash of the circulation fluid which issues from the nozzle under such high velocity and pressure after it encounters the hole bottom in the very near vicinity is such as to abrade away or to cut away the retaining gland or nut and to cut away other surrounding structure to such an extent that the nozzle may loosen and even drop off.

A primary object of the present invention is to provide a well drilling bit of this type wherein the leg that provides the circulation fluid passage has the nozzle so mounted thereon as to effectively resist its being eroded or loosened by the backwash of the issuing stream of circulation fluid. 7

Another object of the present invention is to provide a well drilling bit having the above mentioned characteristics wherein the nozzle is so mounted on the leg that it can be easily removed and replaced when occasion requires, but the design is such that erosion of structure by the backwash of the circulation fluid will not enable the nozzle to drop off and become lost in the hole.

With the foregoing and other objects in view, which will be made manifest in the following detailed description and specifically pointed out in the appended claims, reference is had to the accompanying drawings for an illustrative embodiment of the invention, wherein:

FIGURE 1 is a bottom plan view of a well drilling bit embodying the present invention.

FIGURE 2 is a sectional view taken substantially upon the line 2-2 upon FIGURE 1 in the directions indicated.

Referring to the accompanying drawings, wherein similar reference characters designate similar parts throughout, the well drilling bit embodying the present invention consists of a body 10 which may be constructed in accordance with conventional practice. Usually in accordance therewith, the body is made up of three or more body sections welded together and forming the body, at the top of which there may be a threaded pin 11 providing for the attachment of the bit to the lower end of a well drilllng stern. Some of the segments provide downwardly extending legs 12 on the inner ends of which there are inwardly extending journals 13 on which roller cutters 14, which are usually toothed, are rotatably mounted such as by anti-friction bearings 15. The body 10 provides passages for circulation fluid that are usually terminated in discharge nozzles 16 that are downwardly directed adjacent or between the cutters 14. Because of the fact that the nozzles 16 are disposed above the cutters 14 and are consequently remote from the hole bottom B, the streams of circulation fluid which issue therefrom have very little effect on the hole bottom and are usually incapable of washing away or cutting into the hole bottom B with any noticeable effect. The streams of circulation fluid which issue from the nozzle 16 are used primarily to clean the cutters 14, to wash away cuttings and also to cool the bit.

One of the legs indicated at 17, instead of having a cutter 14 rotatably mounted thereon, is devoted to conducting circulation fluid from the interior of the bit body to a point closely adjacent the hole bottom B. For best results, the spacing of the nozzle in this leg should be within six internal diameters of the nozzle from the hole bottom. To this end, the leg 17 is thickened internally so that it is considerably thicker than any leg 12 and has a circulation passage 18 cored or otherwise formed therein. It is desirable to have the passage 13 as large as is reasonably feasible so that the velocity of the circulation fluid therethrough will have relatively little cutting action therein.

In accordance with the present invention, instead of re taining the nozzle in place by means of a retaining gland or nut, the lower end of the passage 18 is drilled out or enlarged as indicated at 19 forming a downwardly facing shoulder 20 in the lower end of the passage. The nozzle 21 is formed of a hard abrasion-resistant material such as tungsten carbide or a hard ceramic and is designed to snugly fit the interior of the enlarged bore 19 and to abut against the shoulder 20. This nozzle has an internal diameter at its lower or discharge end that is materially smaller than the circulation fluid passage 18 so that the circulation fluid will issue from the nozzle in a relatively small stream, but at high velocity. The length of the nozzle 21 is such that it will protrude beneath or extend below the extreme bottom surface 22 of the leg 17 and in fact, it is desirable to have the entire bottom surface of the nozzle exposed on the bottom surface of the leg 17. Near the top of the enlarged bore 19 there is an annular internal groove 23 formed in the leg, and this groove is largely occupied by an endless rubber O-ring, which serves as a seal preventing leakage of circulation fluid around the nozzle 21 between the nozzle and the body of the leg 17. The bottom surface of the leg 17 is preferably hard faced at 22 with welded on hard facing metal Which will resist abrasion and erosion by the backwashing circulation fluid.

As a means for releasably retaining the nozzle 21 in position in the leg 17, the leg is transversely drilled to provide bores 24 and 25. The nozzle 21 has an annular groove formed on its exterior which intersects the bores 24 and 25 and locking pins or roll pins 26 and 27 are driven in the bores so that these pins partially occupy the annular groove formed in the exterior of the nozzle and partially occupy the bores 24 and 25 that are drilled transversely through the leg 17.

In operation, circulation fluid will be pumped down through the drill stem by the conventional mud pumps and is caused to discharge through the nozzle 16 in a conventional manner. A substantial fraction of the circulation fluid enters the circulation passage 18 in the leg 17 and passes downwardly therethrough at relatively low velocity until it encounters the nozzle 21. The nozzle 21 causes the circulation fluid to be discharged at a relatively high velocity against the bottom of the hole or against the juncture of the bottom of the hole with the well walls. In the preferred arrangement, the spacing of the discharge end of the nozzle 21 from the hole bottom B is less than six internal diameters of the discharge end of the nozzle from the hole bottom so that the effect of the discharging stream will not be dissipated prior to encountering the hole bottom that is formed by the cutters 14.

As above explained, the circulation fluid, after being discharged by the nozzle 21, and encountering the hole bottom B, has quite an abrasive backwash tending to abrade away the lower end of the leg 17 and/or soft metal structure surrounding the nozzle. This is most effective on the exposed surfaces that immediately surround the discharge orifice 28. However, with the present arrangement, inasmuch as the entire lower end of the nozzle is exposed on the bottom surface of the leg 18, the surfaces of the hard nozzle effectively protect the nozzle against the effect of the backwash and keep the nozzle from loosening. Any tendency of the backwash to erode or cut the bottom surface of the leg 17 which surrounds the nozzle 21 is effectively prevented by the welded on hard facing that is applied to the bottom surface of the leg. As the retaining ins 26 and 27 are disposed entirely within the leg and some distance above the bottom surface of the nozzle 21 and the bottom surface of the leg 17,'these retaining pins are effectively protected against erosion by the backwash. At the same time, however, if occasion should require the substitution of nozzles 21 or the replacement of one nozzle by another, the retaining pins 26 and 27 can be readily driven through their respective bores or holes 24 and 25, and the nozzle can then be easily Withdrawn from the enlarged bore 19.

It will be appreciated by those skilled in the art that with the nozzle mounted on the leg 17 in the manner herein disclosed the nozzle in effect affords its own protection against backwash so that it cannot be readily loosened and allowed to drop ofl, as in the case where the nozzle is retained in place such as by a retaining gland or nut.

The improved bit has been designed for use in such earth formations which can be effectively penetrated or washed away by an issuing stream of circulation fluid discharge at high velocity near the hole bottom. It may also be used to advantage in directional drilling in the manner disclosed in my co-pending application. The discharging stream of circulation fluid that is discharged through the orifice 28 is not relied upon solely to accomplish the drilling. It will be appreciated that the improved bit will usually be rotated by the drill stem in the conventional manner and that the roller cutters 14 will perform a substantial portion of the drilling. It is only when the formation is responsive to being penetrated by the stream of circulation fluid that the work performed by the cutters 14 can be materially reduced by the stream of circulation fluid that discharges from the nozzle.

Various changes may be made in the details of construction without departing from the spirit or scope of the present invention, as defined by the appended claims.

I claim:

1. A well drilling bit having a body with three equally spaced legs extending downwardly therefrom with journals on the lower ends of two of the legs, said journals extending downwardly and inwardly from said legs, and roller cutters rotatably mounted on the journals, wherein the improvement comprises: the third leg extending downwardly approximately the same distance as said two legs and having a circulation fluid passage associated therewith and terminating approximately even with the lower end of the third leg and directed downwardly with respect thereto, a nozzle of hard abrasion resisting material in the lower end of said passage having an internal diameter smaller than that of the remainder of the passage, said nozzle having its outlet end protruding below the lower end of said third leg and having a flow path directed unobstructedly toward the bottom of the hole when in use, means disposed entirely within said third leg for retaining said nozzle within said third leg, and said body having additional circulation fiuid discharge nozzles terminating above the cutters and directed downwardly adjacent the sides of the cutters.

2. The structure in claim 1, and the first mentioned nozzle having an outlet of greater capacity than that of each of said additional discharge nozzles.

3. The structure in claim 1, and the first mentioned nozzle being of an abrasion resistant material of greater hardness than that of its supporting leg, and the downwardly facing bottom of that leg, about said nozzle, being provided with welded-on hard facing material.

References Cited UNITED STATES PATENTS 1,855,330 4/1932 Zublin -411 X 2,066,671 1/1937 Catland 175-339 2,087,500 7/1937 Catland 175-340 2,335,929 12/1943 Fortune 175-340 2,885,186 5/1959 Hammer 175-340 2,901,223 8/1959 Scott 175-340 X 3,084,751 4/1963 Scarborough 175-340 3,096,834 7/1963 Steen 175-340 3,113,630 12/1963 Williams 175-340 3,137,354 6/1964 Crawford et al 175-340 3,158,214 11/1964 Wisler et a1 175375 3,207,241 9/1965 Neilson 175-340 3,220,754 11/1965 Mori 175-340 OTHER REFERENCES Bobo, Roy A., et al., Keys to Successful Competitive Drilling in World Oil, 1945(6): pp. 112-114, 117 and 118, Nov. 1957, TN 860.041.

CHARLES E. OCONNELL, Primary Examiner.

I. A. CALVERT, Assistant Examiner. 

1. A WELL DRILLING BIT HAVING A BODY WITH THREE EQUALLY SPACED LEGS EXTENDING DOWNWARDLY THEREFROM WITH JOURNALS ON THE LOWER ENDS OF TWO OF THE LEGS, SAID JOURNALS EXTENDING DOWNWARDLY AND INWARDLY FROM SAID LEGS, AND ROLLER CUTTERS ROTATABLY MOUNTED ON THE JOURNALS, WHEREIN THE IMPROVEMENT COMPRISES: THE THIRD LEG EXTENDING DOWNWARDLY APPROXIMATELY THE SAME DISTANCE AS SAID TWO LEGS AND HAVING A CIRCULATION FLUID PASSAGE ASSOCIATED THEREWITH AND TERMINATING APPROXIMATELY EVEN WITH THE LOWER END OF THE THIRD LEG AND DIRECTED DOWNWARDLY WITH RESPECT THERETO, A NOZZLE OF HARD ABRASION RESISTING MATERIAL IN THE LOWER END OF SAID PASSAGE HAVING AN INTERNAL DIAMETER SMALLER THAN THAT OF THE REMAINDER OF THE PASSAGE, SAID NOZZLE HAVING ITS OUTLET END PROTRUDING BELOW THE LOWER END OF SAID THIRD LEG AND HAVING A FLOW PATH DIRECTED UNOBSTRUCTEDLY TOWARD THE BOTTOM OF THE HOLE WHEN IN USE, MEANS DISPOSED ENTIRELY WITHIN SAID THIRD LEG FOR RETAINING SAID NOZZLE WITHIN SAID THIRD LEG, AND SAID BODY HAVING ADDITIONAL CIRCULATION FLUID DISCHARGE NOZZLES TERMINATING ABOVE THE CUTTERS AND DIRECTED DOWNWARDLY ADJACENT THE SIDES OF THE CUTTERS. 